Effect of Longer Family Meals on Children’s Fruit and Vegetable Intake

This randomized clinical trial assesses the effect of family mealtime duration on fruit and vegetable intake among children.


Methods: Intervention, Participants, Outcome
Study type: Within subject randomized trial.

Time frame: November 2016 -May 2017
Intervention: Two conditions: Usual family meal duration versus 50%-increased duration. The family's usual meal duration will be assessed beforehand (online preassessment at home). Before each lab dinner starts, parent and child are told at which time the experimenter comes back to clear the table (e.g., if the family's usual meal duration was 20 minutes, and the lab dinner started at 6 p.m., then, in the experimental condition, family dyads are told that the experimenter comes back at 6:30; in the control condition at 6:20).

Eligibility Criteria
-Parents must be the household's nutritional gatekeeper -Parents must have at least one child between the age of 6-11 -Participants should not follow a special diet (e.g., no food allergies) -Consent to participate and be video-taped during the lab dinners Randomization -Each parent-child dyad will have two lab dinners, one dinner at usual meal duration, one dinner that takes 50% longer (2 week washing-out phase in between) -Control and intervention condition are presented in randomized order 3 -Randomization technique: Block randomization

Recruitment
Participants are recruited through a participant data base of the lab of the Max Planck Institute for Human Development. Importantly, these participants have not participated in a food or health-related experiment at the institute before. Recruitment and allocation procedure are conducted by the lab manager of the Max Planck Institute for Human development and well as two trained research assistants.

Set-up laboratory meal
All laboratory dinners are recorded with two video cameras (GoPro Hero 4, black edition). The cameras captured the dinners from two different angles (frontal view of the child and frontal view of the parent). The dinner room is set up with plants, pictures on the wall, and cozy lighting to resemble a family dining room. The participants eat foods freely from the options provided on the dinner table, which reflects a typical German dinner: All lab dinners consist of sliced bread, cheese, and cold meat, butter, sweet spreads (e.g., marmalade or hazelnut crème) and pieces of fruits and vegetables of equal size. Beverages provided include water and one sugar sweetened beverage. After the main meal, a dessert is served, consisting of pudding or fruit yogurt and cookies. Importantly, the types of food and beverages served at the lab dinner (e.g., type of vegetable, type of cheese, type of sugar sweetened beverage, type of dessert) matches the child's individual food preferences, as assessed in the preassessment. The family is instructed to not eat anything during the two hours before coming to the institute.

Procedure
Before the lab sessions starts, parents are asked to fill in an online questionnaire at home together with their child (Preassessment). This is to receive information on the child's food preferences and the family's usual meal duration. This information is used to set up the lab dinner. After filling out the online questionnaire, parents are contacted in order to make two appointments for the lab dinners at the Max Planck Institute for Human Development. Directly after each lab session, parents and children complete a short questionnaire about satiety and experiences during the lab meal. Week 3-4 Week 5-6 6

Video coding
The videos are clustered into one double-view movie merging the two recordings and are coded with the coding software datavyu. The coding is conducted by two trained research assistants who are blind to the study purpose. Research assistants participated in several training sessions.
They received information on judgmental biases, family meals and eating behavior in children.
They are introduced to the coding manuals, familiarize with the coding software datavyu and practice coding with videos from the pilot study.

Coding food consumption
We use either standardized measuring spoons and glasses or individual pieces to allow all observers to visually estimate the portions. Food intake during the lab dinner is coded as follow: The kilocalories for each piece of food (e.g. one slice of bread) or for a teaspoon of food (e.g. butter or dessert) are calculated based on their weight and the information from the respective nutrition label.

Coding eating rate
Eating rate is measured as bites taken per minute coded from the videotapes following the procedure described by Llewellyn et al. (2008).
-A bite is counted whenever it is clearly visible that the child bit a piece of a food.
-Nibbling is counted as a bite only when an amount the size of a bite is ingested by several consecutive nibbles -Isolated nibbles are not counted 8 -Amounts smaller than what is defined to qualify as a bite count as a bite only when they are consumed multiple times in a row and the summed-up amount is estimated to equal a bite -Eating rate is calculated by dividing the total number of bites within a time unit by its duration (see data preparation for more details on time units).
-Sucking is not counted as a bite

Preassessment
Before the first lab dinner, parents are asked to fill out an online survey at home together with their child. Variables include: -Demographics (age of the child and the parent, education of the parent) -the family's usual meal duration (parents are asked to measure the duration of the family's next main meal and to use this as a basis to estimate the usual family meal duration). This information is used to determine the meal duration for the lab sessions.
-Child's food preferences: Food preferences of the child are measured using a food questionnaire adapted from Fildes and colleagues. The scale contained 40 food and drink items chosen to cover the range of foods typically served for dinner in Germany (measured 5-point-Likert-type scale, anchored between "dislikes a lot" and "likes a lot"). Based on the results of the preference scale, the top ranked (at least scale point 3, "likes a bit") foods and drinks are chosen for the lab dinner. We add smileys to the scale in order to make it easier for the child to rate their liking of the food: Post-dinner questionnaire • Satiety of the child. A picture rating scale adapted from Bennett & Blissett (2014) is used to rate their hunger and satiety -Satiety of the parent. Sensation of hunger and thirst on a visual analogue scale with the opposites "not hungry at all" and "extremely hungry' (Flint et al., 2000).
-Mealtime atmosphere. Parents were asked to rate the atmosphere of the lab dinner on a 5-point Likert scale ranging from very negative to very positive (Knobl et al., 2022).

Data preparation
Mealtime is converted from minutes to percent to compare children with different usual duration times. So, the videos are divided up into time units: 0%-100% of mealtime refers to the usual meal duration (in both, the control and experimental condition), 100%-150% of mealtime refers to additional time (in the experimental condition only). Start and end time of social interactions, start time of each bite, and each food consumed are exported from datavyu. The frequency and duration of social interactions are calculated in Excel.

Sample size
Sample size is calculated based on a meta-analysis on meal duration and children's nutritional health, using G*Power software. With the assumed effect size of d = 0.4 (with power =.85, alpha =.05), a total sample of 47 families is required. o take better-fitting model; include condition as a Level 2 predictor; use cross-level interaction of the two predictors to explore whether the increase in consumed pieces differs between groups up to the meal duration of 100%

Variables
• paired t-test to test for differences interpersonal communication between meals at usual length and prolonged meals -Wilcoxon signed rank test to test for differences in self-rated atmosphere between meals at usual length and prolonged meals -Wilcoxon signed rank test to test for differences in satiety between meals at usual length and prolonged meals -paired t-tests to test for differences in eating rate between the usual meal duration and longer meal duration condition; dependent variable: bites per minute within the first time unit (i.e. usual meal duration = 100%). We expect the overall eating rate (measured in bites per minute) to decrease in the longer meal duration condition, because it is very likely that children do not eat 50% more when they have 50% more time, which inevitably leads to fewer bites per minute. However, we are interested in the question if children start eating at a slower rate when they have more time to eat. Consequently, we compare the first-100%-time units of both conditions only to test the mechanism of eating rate.
Statistical analyses are performed in R 3.2.3